Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
1999-10-14
2002-05-07
Fenstermacher, David (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S042000, C476S045000
Reexamination Certificate
active
06383112
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toroidal-type continuously variable transmission which can be used as a car transmission or the like.
2. Description of the Related Art
Conventionally, it has been studied to use as a car transmission such a toroidal-type continuously variable transmission as shown in
FIGS. 10 and 11
. In this toroidal-type continuously variable transmission, an input-side disk
2
is supported concentrically with an input shaft
1
which is rotatably supported in the inside of a transmission case (not shown), while an output-side disk
4
is fixed to the end portion of an output shaft
3
which is also supported rotatable with respect to the transmission case. On the inner surface of the transmission case with the toroidal-type continuously variable transmission stored therein, or on a support bracket disposed within the transmission case, there are disposed two trunnions
5
and
5
which can be respectively swung about their associated pivot shafts respectively situated at positions along an imaginary plane that is perpendicular to an imaginary line connecting the respective axes of the input and output shafts
1
and
3
, and distanced from the intersection of the imaginary plane and imaginary line. This physical relation is hereinafter referred to as “torsional relation”.
The two trunnions
5
and
5
are respectively formed of highly rigid metal material, while the above pivot shafts are respectively disposed on the outer surfaces of the two ends of the rigid metal trunnions
5
and
5
in such a manner that they extend concentrically with each other in the front-and-back direction of
FIGS. 10 and 11
. Also, in the peripheries of displacement shafts
6
and
6
which are respectively disposed in the central portions of the two trunnions
5
and
5
, there are rotatably supported power rollers
7
and
7
, respectively. And, these power rollers
7
and
7
are interposed between the input-side and output-side disks
2
and
4
. On the respective one-side surfaces of the input-side and output-side disks
2
and
4
in the respective axial directions thereof, there are formed an input-side concave surface
2
a
and an output-side concave surface
4
a
each of which has an arc-shaped cross section with a point on its associated pivot shaft as a center thereof. And, the peripheral surfaces
7
a
and
7
a
of the power rollers
7
and
7
, which are respectively formed in rotation-arc-shaped convex surfaces, are contacted with the input-side concave surface
2
a
and output-side concave surface
4
a
, respectively.
Also, between the input shaft
1
and input-side disk
2
, there is interposed a pressure device
8
of a loading cam type, while the pressure device
8
pushes the input-side disk
2
toward the output-side disk
4
. The pressure device
8
is composed of a cam plate
9
rotatable together with the input shaft
1
, and a plurality of (for example, 4 pieces of) rollers
11
,
11
, —which are rotatably held by a retainer
10
. On one side surface (in
FIGS. 10 and 11
, the right side surface) of the cam plate
9
, there is formed a cam surface
12
which is a curved surface extending in the circumferential direction of the cam plate
9
; and, at the same time, on the outer surface (in
FIGS. 10 and 11
, the left side surface) of the input-side disk
2
as well, there is formed a similar cam surface
13
. And, the plurality of rollers
11
,
11
, . . . are freely rotatable about their respective shafts extending radially with respect to the center of the input shaft
1
. By the way, the input-side disk
2
is supported in such a manner that it can be slided to a slight degree in the axial direction of the input shaft
1
as well as it can be rotated in the rotation direction of the input shaft
1
.
If the cam plate
9
is rotated with the rotation of the input shaft
1
to thereby produce a rotation phase difference with respect to the input-side disk
2
, then the plurality of rollers
11
,
11
, —are caused to run up onto the two cam surfaces
12
and
13
, thereby causing the cam plate
9
and input-side disk
2
to move away from each other. Since the cam plate
9
is supported on the input shaft
1
carried on the transmission case by a bearing in such a manner that the cam plate
9
is prevented from moving in the axial direction of the input shaft
1
, the input-side disk
2
is pushed toward the power rollers
7
and
7
, so that the power rollers
7
and
7
are respectively pushed toward the output-side disk
4
. On the other hand, the output-side disk
4
is supported to the transmission case in such a manner that it can be only rotated together with the output shaft
3
but is prevented against movement in the axial direction of the output shaft
3
. Therefore, the power rollers
7
and
7
are strongly interposed between the input-side disk
2
and output-side disk
4
. This increases the mutual contact pressures between the peripheral surfaces
7
a
,
7
a
of the power rollers
7
,
7
and the two input-side and output-side concave surfaces
2
a
,
4
a
to a sufficient degree, so that the rotation of the input-side disk
2
can be transmitted to the output-side disk
4
through the power rollers
7
,
7
with little slippage and thus the output shaft
3
with the output-side disk
4
fixed thereto can be rotated.
In changing the rotation speed ratio between the input shaft
1
and output shaft
3
, at first, to decelerate the rotation speed between the input shaft
1
and output shaft
3
, as shown in
FIG. 10
, the trunnions
5
and
5
are respectively swung in a given direction about their respective pivot shafts to incline the displacement shafts
6
and
6
in such a manner that the peripheral surfaces
7
a
and
7
a
of the rollers
7
and
7
can be respectively contacted with the portion of the input-side concave surface
2
a
located near the center portion thereof and the portion of the output-side concave surface
4
a
located near the outer periphery thereof. On the other hand, to accelerate the rotation speed between the input shaft
1
and output shaft
3
, as shown in
FIG. 11
, the trunnions
5
and
5
are respectively swung in the opposite direction to the above direction to incline the displacement shafts
6
and
6
in such a manner that the peripheral surfaces
7
a
and
7
a
of the rollers
7
and
7
can be respectively contacted with the portion of the input-side concave surface
2
a
located near the outer periphery thereof and the portion of the output-side concave surface
4
a
located near the center thereof. Also, if the inclination angles of the displacement shafts
6
and
6
are respectively set in the middle of the angles shown in
FIGS. 10 and 11
, then there can be obtained an intermediate gear ratio between the input shaft
1
and output shaft
3
.
The basic structure and operation of the toroidal-type continuously variable transmission are as described above. By the way, when using such toroidal-type continuously variable transmission as a transmission for a car including a large output engine, in order to be able to secure the power that can be transmitted, there is employed a structure in which the input-side disks
2
and output-side disks
4
are disposed by twos. In this toroidal-type continuously variable transmission of a so called double-cavity type, the two input-side disks
2
and two output-side disks
4
are respectively arranged in parallel to each other with respect to the transmission direction of the power.
FIG. 12
shows an example of a toroidal-type continuously variable transmission of a double-cavity type which has been proposed for the above object.
In the conventional structure shown in
FIG. 12
, a torque transmission shaft
15
, which is a rotary shaft, is supported inside a housing
14
in such a manner that it can be only rotated. And, the torque transmission shaft
15
can be freely driven or rotated by a drive shaft
16
which is connected to the output shaft of a clutch or the like. Also, on the axial-direction two
Fujinami Makoto
Goto Nobuo
Imanishi Takashi
Itoh Hiroyuki
Kato Hiroshi
Fenstermacher David
Joyce William C.
NSK Ltd.
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